The present invention relates to the field of telecommunications and more specifically of a mobile device connecting simultaneously to multiple networks using mobile IP protocol (MIP) and managing accordingly its at least one DNS identity as visible to other internet nodes.
The Domain Name System (DNS) allows nodes connected to the internet to know each other by using logical names (Fully Qualified Domain Name). This allows nodes to be independent of IP addresses they are assigned at a particular time. Logical names are permanent and represent logical identities of machines while IP addresses are volatile and represent physical addresses where machines can be reached through the internet infrastructure. Specific servers, the Domain Name Servers, maintain relationships between domain names and IP addresses and perform translation between logical names and IP addresses.
To support mobile nodes, routers called home agents (HA) perform tunnelling of data packets from a globally reachable home address (HoA) of the node to a locally assigned IP address of an interface of the mobile node, known as care-of-address (CoA). Said interface is connected at a point in the network corresponding to the geographic position of the mobile node. The care-of-address is updated with the home agent in regular binding update messages, indicating to the home agent where it has to forward the incoming data packets. In addition, a home agent performs updates in the DNS system on behalf of the mobile node to maintain the relationship between the mobile node logical identity (Fully Qualified Domain Name, FQDN) and its current home addrss.
Mobile nodes with multiple interfaces have multiple home addresses each assigned by a separate home agent. Such a mobile node is thus reachable through multiple home
addresses. Accordingly, such a mobile node might also be known under either a single logical identity (single FQDN) or multiple logical identities (multiple FQDN) depending on relationships between the home agents and the DNS infrastructure. When the home agents are in the same DNS domain, the mobile node has a single FQDN. When the home agents are in different DNS domains, the mobile node has multiple FQDN.
In the current state of the art, the mobile node attaches through each of its multiple interfaces, obtains a care-of-address, the address of a home agent and a home address. It then binds the home address and care-of-address to the home agent requesting for DNS update. Since no specific mechanism is currently defined to handle the multiple interfaces case, the DNS update process leads to the following behaviours:                in the single FQDN case, the lastly bound home address is always mapped to the FQDN, leading to the use of only the one associated interface at mobile node level,        in the multiple FQDN case, the mobile node is known under separate and unrelated logical identities by the outside world, leading to potential lack of connectivity when one of the mobile interfaces drops.        
Both behaviours prevent the mobile node and its correspondents to take full benefit of the multiple-interface capabilities.